"60. AG Tagung" - 2013
Beitrag - Modul 1
Vortrag 2.2 - Zwischenergebnisse eines Langzeitfeldversuchs mit Bienenvölkern, die mit 200 oder 2000ppb Thiacloprid haltigem Zuckersirup gefüttert wurden.
Reinhold Siede, L. Faust, C. Maus, M. Meixner, B. Grünewald, R. Büchler (Kirchhain, Oberursel)
E-Mail: reinhold.siede@llh.hessen.de
Abstractband (Pflanzenschutz & Bestäubung, S. 14-15):
Some neonicotinoides are highly toxic to honeybees. However, cyano-substituted compounds as thiacloprid are intrinsically less toxic. Laboratory assays have shown that bees can effectively detoxify thiacloprid. However, there are concerns about potential long-term effects on the colonies under field conditions. To identify potential hazards colonies were chronically fed with sublethal concentrations of thiacloprid and observed for 10 months. We report results from the first 2 years from a planned period of 3 years. In July 2011 and July 2012, respectively, 30 colonies were started from shook swarms, divided into three groups with ten colonies each, and migrated to an experimental yard. Five times per autumn they were provided with sugar syrup containing either 200 ppb or 2000 ppb thiacloprid or syrup alone (control). Every 3 weeks the colonies were weighed, their brood area measured and their strengths estimated. Dead bees were counted in entrance traps. Honey and bee bread were sampled two times per year for analyzing residues of thiacloprid using LC-MS/MS. At the end of the feeding periods differences between groups in number of bees and brood per colony were low (means from 2011: control: 13,200 bees; 3,462 brood cells; 200ppb: 11,980; 3,503; 2000ppb: 11,133; 2,543; means from 2012: control: 8,590; 2,403; 200ppb: 9,175; 1,792; 2000ppb: 8,075; 2,243). The data will be statistically analyzed with linear mixed models. Residues of thiacloprid in honey did not significantly correlate with the number of bees, of brood and dead bees (spearman rang correlation, p≥0.09, 90 observations). No winter loss occurred. So far our study does not indicate that colony vitality parameters are affected by a long-term feeding with 200 or 2000ppb thiacloprid. This study is part of the FITBEE-project supported by funds of the German Federal Ministry of Food, Agriculture and Consumer Protection (BMELV) via the Federal Office for Agriculture and Food (BLE) under the innovation support program.
Beitrag - Modul 3
Poster P13 - Effekte einer optimierten Applikationstechnik (Dropleg) auf die Pollen- und Nektarkontamination im Winterraps.
Klaus Wallner, C. Maus, M. Tritschler, R. Friessleben, R.-B. Toews (Hohenheim, Monheim)
E-Mail: Klaus.Wallner@uni-hohenheim.de
Abstractband (Pflanzenschutz & Bestäubung, S. 45-46):
Oilseed rape is one of the most important agricultural crops in Germany (cropping area > 1.5 mio ha), and likewise of key importance in beekeeping as early-season bee forage.
To prevent losses of yield, oilseed rape has to be treated with different pesticides during blooming season. The application of pesticides into the blossoms has led to residue findings in honey which caused concerns by beekeepers. We present a concept to optimize pesticide application technology, towards minimization of exposure of bees to pesticide residues in treated blossoms.
The under-leaf application technology is a modified system (Dropleg) that has been used in vegetable crops for several years. In semi-field and field trials in 2011 and 2012 it was tested in how far under-leaf spray with the Dropleg system in flowering oilseed rape can reduce pesticide residues in nectar and pollen collected by exposed bee colonies in comparison to conventional application technology. Pollen loads and stored nectar of experimental bee colonies were sampled at different points of time after application and analyzed for pesticide residues. As model substances, a systemic fungicide and a non-systemic insecticide were applied, in 2012 additionally a systemic insecticide. First results from 2011 suggest that Dropleg application can significantly reduce pesticide exposure of bee colonies. The project is conducted in the scope of the FitBee Project supported by German BMELV and will be continued until 2014.
Beiträge - Modul 4
Vortrag 2.5 - Interaktionen zwischen Mikrosporidien, Viren und Pestizide bei ihrem Einfluss auf Larven und erwachsenen Honigbienen.
Vincent Doublet, M. Labarussias, M. E. Natsopoulou, J. Steinberg, A. Miertsch, J. R. de Miranda, R. J. Paxton (Halle, Allg. Zool., Uppsala)
E-Mail: robert.paxton@zoologie.uni-halle.de
Abstractband (Pflanzenschutz & Bestäubung, S. 17):
There are many factors that can precipitate the decline and death of honeybee colonies. What is less-well known is how these factors affect each other. In recent studies, focus has been placed on the interactions among several potential ‘stressors’, and particularly on the interaction between disease-causing microorganisms and sub-lethal doses of pesticides. Our research investigated how the interactions among pathogens and pesticides affect individual honey bees. We studied these interactions both in adults, with cage experiments, and in larvae using in vitro rearing techniques, using the microsporidian Nosema ceranae, a common virus (black queen cell virus - BQCV) and a widely used insecticide (Thiacloprid), fed to larvae and adults at sub-lethal doses. We detected multiple interactions during our experiments. In larvae, we observed an interaction between the BQCV and Thiacloprid that affected both survivorship and development (pupation). In adults, interactions between the virus and the insecticide were also observed, but to a lesser extent than between N. ceranae and Thiacloprid, suggesting that these two pathogens interact differently with the pesticide or induce a different response in the honey bee. The interaction that led to the greatest impact on honey bee mortality was that between BQCV and N. ceranae. Co-infected adult bees had a much higher mortality than all other treatments, suggesting a synergistic interaction between these two pathogens. These observations support the idea that co-infection by multiple pathogens could be a significant factor of honey bee decline. However, the causal mechanisms of the interaction between them are still unclear. We acknowledge support of the EU (project: Bee Doc) and the BMELV/BLE (project: Fit Bee).
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Vortrag 4.4 - DWV/VDV-1 und Winterverluste bei Honigbienenkolonien in Deutschland.
Myrsini E. Natsopoulou, D. P. McMahon, V. Doublet, V. Maibach, E. Frey, P. Rosenkranz, R. J. Paxton (Halle, allg. Zool., Hohenheim)
E-Mail: peter.rosenkranz@uni-hohenheim.de, robert.paxton@zoologie.uni-halle.de
Abstractband (Bienenpathologie, S. 25):
Winter mortality is a prime cause of colony loss in Europe, and honey bee colonies suffering elevated worker losses over winter are likely to be more prone to collapse. To explore an explicit cause of colony decline during winter, workers from colonies either treated or untreated in autumn to control Varroa destructor were sampled in autumn 2011 and the following spring 2012. We used a PCR-based multiplex ligation analysis (MLPA) to monitor the presence/absence of seven viral targets as well as Nosema spp. Levels of overwinter worker mortality within their colonies were also recorded. Quantitative RT-PCR was used to assess infection level of the most prevalent pathogens in pooled and individual samples of worker bees. Preliminary analyses indicate that autumn 2011 honey bees carried a heavy burden of VDV-1 (biologically close to DWV) and BQCV independent of Varroa-treatment but, in spring 2012, the level of VDV-1 in workers was low, suggesting that infected workers had died during the winter. Conversely, BQCV titres in workers did not change between seasons. Untreated colonies suffered higher worker losses compared to treated colonies. In order to corroborate our hypothesis derived from our field observations that the DWV/VDV-1 family of viruses has a significant impact on honey bee winter morality, we used a controlled laboratory experiment to inject autumn bees with DWV/VDV-1. Our results support the notion that DWV and related viruses are a major cause of worker mortality and colony collapse. We acknowledge support of the BMELV/BLE (project: Fit Bee), the EU (project: Bee Doc) and the BBSRC’s Insect Pollinators Initiative (project: Emergent Diseases).
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Poster P43 - Konkurrenz zwischen den zwei intrazellularen Krankheitserregern Nosema apis und Nosema ceranae im Mitteldarm der Honigbiene Apis mellifera.
Myrsini E. Natsopoulou, D.P. McMahon, V. Doublet, R.J. Paxton (Halle, Allg. Zool.)
E-Mail: robert.paxton@zoologie.uni-halle.de
Abstractband (Bienenpathologie, S. 65):
Nosema apis and Nosema ceranae are two microsporidian species that commonly infect honey bees (Apis sp.). Both species are obligatory intracellular pathogens that multiply within the epithelial cells of the ventriculus of their hosts. While N. ceranae was originally detected in the Asian honey bee Apis ceranae, recent studies have demonstrated it to be an emergent parasite of the western honey bee Apis mellifera, and present in Europe since at least 1997. Moreover, due to its widespread distribution and high prevalence, it has been suggested that N. ceranae is replacing the native N. apis, at least in some host populations. As part of the Fit Bee project, we compared the growth of these two Microsporidia after challenging individual honey bees (A. mellifera) with a single Microsporidia or with both. Sequential as well as mixed in vivo infection experiments were performed using newly emerged bees, and infection levels were determined 14 days post treatment by quantitative PCR. We thereby test the asymmetry of the competition between the original versus emerging infectious microsporidian pathogen of the honey bee A. mellifera. Our results help explain why N. ceranae has become an emergent pathogen of the western honey bee worldwide. We acknowledge support of the BMELV/BLE (project: Fit Bee), the EU (project: Bee Doc) and the BBSRC’s Insect Pollinators Initiative (project: Emergent Diseases).
Beitrag - Modul 5
Vortrag 5.2 - Gleiche Ergebnisse bei gleicher Vorgehensweise? Vergleich 2011 & 2012 des FitBee Moduls 5.
W. von der Ohe, Dorothee J. Lüken (Celle)
E-Mail: dorothee.lueken@laves.niedersachsen.de
Abstractband (Bienenprodukte & Sonstiges, S. 30):
Das Kooperationsprojekt FitBee (BLE, BMELV) geht mit der Auswinterung 2012/2013 in die dritte Runde. Somit ist die Möglichkeit gegeben, die Ergebnisse der ersten beiden Jahre miteinander zu vergleichen.
Während der Bienensaison 2011 sowie auch 2012 standen Bienenvölker an Standorten mit unterschiedlichen Standortfaktoren: Gruppe A stand an landwirtschaftlichen Nutzflächen mit guter Nektarversorgung im Frühjahr und an Standorten mit schlechter Nektarversorgung im Sommer und Herbst, Gruppe B an blühenden Agrarflächen im Frühjahr, an Blühstandorten mit hoher Diversität im Sommer, beide mit guter Nektarversorgung, aber an landwirtschaftlich genutzten Flächen im Herbst mit schlechter Nektarversorgung. Gruppe C hatte eine große Blühvielfalt mit guter Nektarversorgung über das gesamte Jahr zur Verfügung. Regelmäßig wurden Populationsschätzungen durchgeführt, neben Bienenproben wurden Bienenbrotproben sowie Honigproben genommen, 2012 wurden zusätzlich Pollenfallen eingesetzt.
Wie unterscheiden sich die Jahre im Hinblick auf den Pollen- und Nektareintrag sowie den damit verbundenen Eintrag von Pflanzenschutzmittelrückständen? Können schon allgemeingültigere Aussagen über die verschiedenen Standorte gemacht werden?
Grundsätzlich waren die beflogenen Pflanzen über den Jahresverlauf an den verschiedenen Standorten zwischen den Jahren ähnlich, dennoch haben sich ganz klar Änderungen in der Nutzung von Agrarflächen in den Pollenanalysen abgezeichnet. In den Bienenbrotproben wurden im Jahr 2011 25 verschiedenen Wirkstoffe gefunden und im Honig ein Wirkstoff, 2012 waren es 36 verschiedene Wirkstoffe im Bienenbrot, bzw. Pollen aus der Pollenfalle und wiederum wurde nur ein Wirkstoff im Honig analysiert.
Für die Auswertung der Populationsschätzungen befindet sich mit dem Projektpartner IP SYSCON eine Datenbank im Aufbau, die Teil eines Fachinformationssystems für Imker sowie weiteres interessiertes Fachpublikum werden wird.
Beitrag - Modul 7
Poster P42 - Störung der Paarung von Varroa destructor in einem Laborbiotest.
Bettina Ziegelmann, P. Rosenkranz (Hohenheim)
E-Mail: Bettina.Ziegelmann@uni-hohenheim.de
Abstractband (Bienenpathologie, S. 64-65):
Male Varroa destructor mate almost exclusively with the youngest adult daughter within a brood cell. Previous studies showed that the observed preference is triggered by a volatile sex pheromone which is presumably released by the females shortly after moulting (Ziegelmann et al., 2013, (doi:10.1007/s13592-012-0182-5). Within the cooperation project „FITBEE“ we identified three fatty acids and the respective ethyl esters in extracts of attractive females as active components of the sex pheromone. In order to evaluate the potential of a biological control of Varroa destructor on the basis of this pheromone, we tested in the current study how the pheromone influences the male mating behavior under laboratory conditions. Therefore, mixtures of these substances were applied on filter paper in different dosages (1 ng, 10 ng, 100 ng, 1000 ng per substance) and the male copulatory responses toward.
The female members of a typical “Varroa family” 8 to 9 days after cell capping – consisting of a mother mite, two mature daughters, a deutochrysalis and a deutonymph – were quantified. Compared to control tests without additional pheromone, males showed for all dosages reduced copulatory responses toward the youngest mature daughter, with the maximum reduction at 100 ng per substance. Obviously, the males’ ability to recognize the “right females” within the artificial pheromone plume was reduced. Instead, an increased seeking behavior and numerous copulation attempts with immature deutonymphs and deutochrysalis as well as older mature daughters could be observed. In regard to a mating disruption technique these results are quite promising and constitute a basis for first application tests in bee colonies.